DC-DC converters with voltage boost capability are widely used in a large number of power conversion applications, from fraction-of-volt to tens of thousands of volts at power levels from milliwatts to megawatts. The literature has reported on various voltage-boosting techniques, in which fundamental energy storing elements (inductors and capacitors) and/or transformers in conjunction with switch(es) and diode(s) are utilized in the circuit. These techniques include switched capacitor (charge pump), voltage multiplier, switched inductor/voltage lift, magnetic coupling, and multistage/-level, and each has its own merits and demerits depending on application, in terms of cost, complexity, power density, reliability, and efficiency. To meet the growing demand for such applications, new power converter topologies that use the above voltage-boosting techniques, as well as some active and passive components, are continuously being proposed. The permutations and combinations of the various voltage-boosting techniques with additional components in a circuit allow for numerous new topologies and configurations, which are often confusing and difficult to follow. Therefore, to present a clear picture on the general law and framework of the development of next-generation step-up dc-dc converters, this paper aims to comprehensively review and classify various step-up dc-dc converters based on their characteristics and voltage-boosting techniques. In addition, the advantages and disadvantages of these voltage-boosting techniques and associated converters are discussed in detail. Finally, broad applications of dc-dc converters are presented and summarized with comparative study of different voltage-boosting techniques.

Bidirectional DC-DC power converters are increasingly employed in diverse applications whereby power flow in both forward and reverse directions are required. These include but not limited to energy storage systems, uninterruptable power supplies, electric vehicles, and renewable energy systems, to name a few. This paper aims to review these converters from the point of view of topology as well as control schemes. From the point of view of topology, these converters are divided into two main categories, namely non-isolated and isolated configurations. Each category is divided into eight groups along with their respective schematics and a table of summary. Furthermore, the common control schemes and switching strategies for these converters are also reviewed. Some of the control schemes are typically applied to all DC-DC power converters such as PID, sliding mode, fuzzy, model predictive, digital control, etc. In this context, it should be noted that some switching strategies were designed specifically for isolated bidirectional DC-DC converters in order to improve their performance such as single phase shift, dual phase shift, triple phase shift, etc. The features of each topology and control scheme along with their typical applications are discussed, in order to provide a ground of comparison for realizing new configurations or finding the appropriate converter for the specific application.

Maximum power point tracking (MPPT) techniques have been vastly researched and developed in order to obtain the maximum terminal power of photovoltaic (PV) arrays in the solar renewable energy system. The aim of this paper is to present a new principal scheme-based review of the categorised MPPT methods (conventional, novel, and hybrid) with respect to the deployment of their input variables (solar irradiance, PV arrays’ temperature, and PV arrays’ terminal voltage and current), where MPPT methods are categorised to six different schemes. For each scheme, previous MPPT studies are extracted from literature and analysed. Then the critical benefits and limitations of the six presented MPPT schemes are compared and discussed. It is concluded that those MPPT schemes deploying the measured external variables would be able to track the global maximum power point with high reliability; however, their implementation cost and applicability remains as a challenge due to increasing the sensor deployment cost and complexity. The conclusion of this paper will help new researchers to deliberately select an appropriate MPPT scheme based on their projects’ objectives and limitations, prior to selecting an optimisation algorithm for MPPT.

A new transformer‐less buck–boost converter is proposed, which owns a quadratic voltage gain ratio. The proposed converter (a) has only one active switch, which makes the implementation of the gate driver and control system simpler; (b) has a quadratic voltage gain without using a transformer, which equips the designers to obtain a high‐voltage gain ratio and avoid the complexity of magnetic utilisations; (c) works both in step‐up or step‐down mode, while most of the existing quadratic topologies are able to work either in step‐up or step‐down mode; and (d) shares a common ground between the input and output terminals. The operating states of the proposed converter along with its steady‐state performance are analysed. Then, the small‐signal modelling and the power loss analysis are performed. A comparison shows the unique features of the converter, specifically in terms of voltage gain ratio and the count of power switches. Finally, the experimental results of a laboratory prototype, as well as the simulation results from PSIM software, are used for validation. The converter was tested in different conditions to inspect its transient response and to record its efficiency. The maximum recorded efficiencies in boost and buck modes, respectively were 94.7 and 93%.

This study proposes a novel DC-DC converter topology that features a quadratic buck-boost voltage gain ratio. The quadratic gain of the converter enables it to achieve superior step-down or step-up capability when the duty cycle is higher or lower than 50 percent, as compared to conventional buck-boost converters. While there exist other quadratic buck-boost converters in the literature, the proposed converter offers unique features such as continuity of input and output currents, which reduces the current stress on the input and filter capacitors, making it a suitable option for renewable energy applications. Additionally, unlike its counterparts that have two high-side switches, the proposed converter features only one high-side and one low-side switch, allowing for a simpler gate-driver design. The proposed topology shares a common ground between the load and the source, and has the lowest stored energy with the same performance, indicating a compact size. Steady-state analysis has been conducted in both continuous and discontinuous conduction modes, and the controller design was studied with the aid of small-signal modelling. Simulation and experimental results from a 100 W prototype were used to validate claims and analyses.

Electric vehicles (EVs) with multi-speed transmission offer improved performances compared to those with single speed transmission system in terms of top speed, fast acceleration, or gradeability along with driving range. In this study, relevant literature is extensively analyzed to explor